Roughly chop 500g of celeriac and dice the remainder into rice-sized grains.
Simmer the celeriac peel in 500ml water for 30 minutes, then strain and reserve the stock.
Boil the thick celeriac chunks for 12 minutes, then blend with 50ml vinegar until smooth.
Boil winkles in salted water with 1 tsp vinegar for 1 minute, then clean and de-shell.
Simmer the cleaned winkles in chicken stock for 45 minutes.
Sauté the diced celeriac in butter, adding celeriac stock gradually until tender.
Stir in the truffle, mascarpone, parmesan, reduced stock, and the prepared winkles.
Spread the purée in bowls, top with the risotto, and garnish with pomelo and celery leaves.